1. Field of the Invention
This invention relates to stereophonic systems, and more particularly, to a three-track stereophonic system.
2. Description of Prior Art
Reference U.S. Pat. Nos. 3,679,832, Halpern, Berkovitz et al 4,074,083, Boudouris et al 4,293,821, and Dolby et al 4,024,344. The references disclose hardened, correllated, and compared center channel signals. The system in accordance with the present invention enables a true center-channel signal to be derived, by combining the left and right signals into a monophonic signal and cancelling and overriding this monophonic signal with a second monophonic signal, and the latter is derived by combining properly bandpassed left and right signals that have been compressed, and expanded. True left-and true right-channel signals are subsequently derived by subtracting the true center-channel signal voltage from the left and right signal voltages.
The principal object of this invention is to provide a three-track stereophonic system that will be a unique and novel electronic system designed to enhance the special characteristics of true stereophonic reproduction of sound, via standard stereo two-track sources, such as, tape, disc, film, and the like, by reprocessing the two-track format into three and possibly more distinct sound sources, without sacrificing the integrity of the original stereophonic recording. The present invention is engineered around the capable function block devices of the Signetics NE570N compandor and the ubiquitous National LM324 quad operational amplifier, without which, would be impractical in terms of moderate cost to the consumer.
Another object of this invention is to provide a three-track stereophonic system, which will overcome the obstacles in performance associated with antedated three-track systems which employ derived-channel monophonic circuitry in producing a third center channel sound track, and the present invention in essence, will produce a true center channel sound track, sonically and divorced from the reproduced stereophonic image, without the use of psycho-acoustic principles or gimmicks, and will demonstrate a freedom of flexibility, comparable to commercial multi-track sound systems beyond the reach of the average consumer, with the exception, of theaters, concert halls, and expensive multi-track home systems.